The present invention discloses a portable hand-held electron gun for space on-orbit operation, belonging to the technical field of space environment material processing. The handheld electron gun mainly comprises an external focusing coil, an electron gun shell, an operating handle and an electron gun core contained inside the electron gun shell. One end of the electron gun housing is fixedly connected with the anode mounting flange, and the other end is fixedly connected with the operating handle. The insulator control is fixedly connected with the inner surface of the electron gun housing to connect one end of the operating handle. One end surface of the cathode holder is fixedly connected with the cathode, and the other end is connected with the anode and the cathode of a connecting electrode. The binding electrode is fixedly connected with the cathode holder and is connected with the anode or the cathode of the connecting electrode, and the cathode and the binding electrode form an equipotential. The anode and the focusing coil are respectively fixed on both sides of the anode mounting flange and the anode is connected with the equipment's earth line. The anodes and the cathodes of a cathode high voltage power supply connector, the focus coil joint and the equipment's earth line are respectively connected with the anode and the cathode of the connecting electrode.